Fisher is Dan's Cat. He is the son of Jordan's cats Shepard and Tali, and the brother of Moh-Ding (which was given to James) Jordan gave them the kittens probably because he didn't want to look after more cats. He is named after Sam Fisher from Splinter Cell, one of Dans Favorite Games.
Fisher (as seen in Cinematic Fisher)
Fisher (Left) and Moh-Ding playing.